2,617 research outputs found
Density and reproductive characteristics of female brown bears in the Cantabrian Mountains, NW Spain
Here we present annual nearest-neighbour distances (as a proxy of density) between females with cubs-of-the-year (hereafter FCOY) and reproductive characteristics of brown bears Ursus arctos in the Cantabrian Mountains (NW Spain), from 1989 to 2017. FCOY nearest-neighbour distances and reproduction parameters of 19 focal females followed over several consecutive years (from 2004 to 2017) were obtained from bears inhabiting the western sector of the Cantabrian Mountains, where most of the bear population resides. In contrast, general reproductive characteristics were studied in the whole Cantabrian Mountains (western and eastern sectors together) on a sample of 362 litter sizes and 695 cubs. Mean nearest-neighbour distance between FCOY was 2559 ± 1222 m (range = 1305–4757 m). Mean litter size was significantly larger in the west (1.8 ± 0.2 cubs) than in the east (1.3 ± 0.6 cubs). Mean litter size for the whole of the Cantabrian Mountains was 1.6 ± 0.3 cubs. Litter sizes of one, two and three cubs represented 33.4, 56.1 and 10.5% of observed family groups, respectively. Interannual variations in litter size were not significant for both the western and the eastern areas. Mean cub mortality was 0.2 ± 0.5 cubs and did not vary among years. Cub mortality per litter size was 3.9% for one cub, 69.2% for two cubs and 26.9% for three cubs. Mean reproductive rate of the 19 focal females was 1.5 ± 0.6 cubs (n = 58 litters). Litter size of focal FCOY did not differ from the litter size obtained from systematic observations in the whole Cantabrian Mountains. During this period, cub mortality occurred in 24.1% of the 58 litters. Females usually bred every second year (average litter interval = 2.2 years). The estimated reproductive rate for the bear population was 0.7 young born/year/reproductive adult female
Ballistic resistivity in aluminum nanocontacts
One of the major industrial challenges is to profit from some fascinating
physical features present at the nanoscale. The production of dissipationless
nanoswitches (or nanocontacts) is one of such attractive applications.
Nevertheless, the lack of knowledge of the real efficiency of electronic
ballistic/non dissipative transport limits future innovations. For multi-valent
metallic nanosystems -where several transport channels per atom are involved-
the only experimental technique available for statistical transport
characterization is the conductance histogram. Unfortunately its interpretation
is difficult because transport and mechanical properties are intrinsically
interlaced. We perform a representative series of semiclassical molecular
dynamics simulations of aluminum nanocontact breakages, coupled to full quantum
conductance calculations, and put in evidence a linear relationship between the
conductance and the contact minimum cross-section for the geometrically favored
aluminum nanocontact configurations. Valid in a broad range of conductance
values, such relation allows the definition of a transport parameter for
nanomaterials, that represents the novel concept of ballistic resistivity
Tratamiento artroscópico de las roturas masivas del manguito rotador
La reparación artroscópica de las roturas masivas del manguito rotador (RMMR) es un procedimiento
técnicamente exigente, que requiere de una indicación correcta, una buena técnica artroscópica y un
adecuado tratamiento rehabilitador. El estudio clínico del paciente y las características de la lesión del manguito
son fundamentales para establecer el plan estratégico y terapéutico, que debe incluir desde el tratamiento no
quirúrgico hasta la reparación artroscópica, transferencias tendinosas artroscópicas, espaciadores subacromiales
o artroplastias de hombro. La reparación artroscópica se establece en pacientes con roturas masivas reparables
y sin degeneración grasa del manguito, las transferencias tendinosas se indican en pacientes jóvenes con importantes
exigencias funcionales que presentan roturas masivas irreparables y los espaciadores subacromiales y las
artroplastias de hombro para roturas irreparables en pacientes con baja demanda funcionalThe arthroscopic repair of a massive rotator cuff tear, is a technically demanding procedure. It
requires correct indications, good arthroscopic skills and a proper rehabilitation program. The clinical study of
the patient and the instances of the rotator cuff injury, are fundamental to determine a correct therapeutic strategy.
This strategy should consider every option from non-surgical to arthroscopic repair, tendon transfers, subacromial
spreaders or shoulder arthroplasties. The arthroscopic repair is the standard treatment in patients with
massive repairable tears and with no fatty degeneration of the affected muscle. Meanwhile, the tendon transfers
are indicated in young patients with highly functional demands that comprehend irreparable massive tears. The
spreaders or subacromial balloons and the shoulder prosthesis are performed in irreparable tears in low functional
demand patients
Examples of signature (2,2) manifolds with commuting curvature operators
We exhibit Walker manifolds of signature (2,2) with various commutativity
properties for the Ricci operator, the skew-symmetric curvature operator, and
the Jacobi operator. If the Walker metric is a Riemannian extension of an
underlying affine structure A, these properties are related to the Ricci tensor
of A
Tele-Rehabilitation Versus Local Rehabilitation Therapies Assisted by Robotic Devices: A Pilot Study with Patients
The present study aims to evaluate the advantages of a master-slave robotic rehabilitation therapy in which the patient is assisted in real-time by a therapist. We have also explored if this type of strategy is applicable in a tele-rehabilitation environment. A pilot study has been carried out involving 10 patients who have performed a point-to-point rehabilitation exercise supported by three assistance modalities: fixed assistance (without therapist interaction), local therapist assistance, and remote therapist assistance in a simulated tele-rehabiliation scenario. The rehabilitation exercise will be performed using an upper-limb rehabilitation robotic device that assists the patients through force fields. The results suggest that the assistance provided by the therapist is better adapted to patient needs than fixed assistance mode. Therefore, it maximizes the patient’s level of effort, which is an important aspect to improve the rehabilitation outcomes. We have also seen that in a tele-rehabilitation environment it is more difficult to assess when to assist the patient than locally. However, the assistance suits patients better than the fixed assistance mode.This work was funded by the Conselleria d’Educacio, Cultura i Esport of Generalitat Valenciana by the European Social Fund—Investing in your Future, through the grant ACIF 2018/214, PEJ2018-002684-A and PEJ2018-002670-A, and by the Spanish Ministry of Science and Innovation through the project PID2019-108310RB-I00
The planetary nebula NGC 1360, a test case of magnetic collimation and evolution after the fast wind
The central star of this nebula has an observed intense magnetic field and
the fast wind is no longer present, indicating that a back flow process has
probably developed. Long-slit, spatially resolved echelle spectra have been
obtained across the main body of NGC 1360 and over its system of bipolar jets.
Deep images of the knotty structures of the jets have also been obtained. The
data allow a detailed study of the structure and kinematics of this object and
the results are modeled considering the effects of a magnetic collimation
process in the development of the nebula and then switching off the fast
stellar wind to follow its evolution to its current state. The model is able to
successfully reproduce many of the key features of NGC 1360 under these
premises.Comment: 16 pages, 7 figures. ApJ in pres
Circumstellar envelopes of semi-regular long-period variables: mass-loss rate estimates and general model-fitting of the molecular gas
We aim to study the main properties of a volume-limited unbiased sample of
well-characterized semi-regular variables (SRs) in order to clarify important
issues, such as the formation of axially symmetric planetary nebulae (PNe) from
spherical circumstellar envelopes (CSEs), which takes place during the
mass-loss process along the AGB phase. We present new high-S/N IRAM 30m
observations of the 12CO J=2-1, J=1-0, and 13CO J=1-0 lines, in a
volume-limited sample of SRs. We analyzed the data by characterizing the main
properties of the CSEs. The 12CO J=2-1 data were used to study the profiles,
while the 12CO J=1-0 data were used to estimate mass-loss rates for the
complete sample. We have classified the sources into four groups according to
the different profiles and final gas expansion velocities. Type 1 and 2
profiles are broad and narrow symmetric lines, respectively. Type 3 profiles on
the contrary are strange profiles with very pronounced asymmetries. Finally,
type 4 profiles are those showing two different components: a narrow line
profile superimposed on a broad pedestal component. Interestingly, we report a
moderate correlation between mass-loss rates and 12CO J=1-0/J=2-1 line
intensity ratios for O-rich SRs, suggesting a different behaviour between C-
and O-rich SRs. Using SHAPE+shapemol, we find a unified simple model based on
an oblate spheroid placed in different orientations that may explain all the
12CO profiles in the sample, indicating that the gas expansion is in general
predominantly equatorial. Moreover, in order to explain the type 4 profiles, we
define an extra component which may somehow be a biconical structure or
similar. Type 1 and 2 profiles, curiously, may also be explained by standard
spherically symmetric envelopes. We conclude that most circumstellar shells
around SRs show axial, strongly nonspherical symmetry.Comment: 32 pages, 28 figures, and 10 tables, accepted for publication in A&
Polyamines containing naphthyl groups as pH-regulated molecular machines driven by light
A series of compounds made up by linking methylnaphthalene fragments at both ends of different polyamine chains have shown to behave as pH-regulated molecular machines driven by light and fluorescence emission studies have proved the formation of an excimer between the two naphthalene units whose appearance, fluorescence intensity and decay times depend on the pH value of the media.Albelda Gimeno, Maria Teresa, [email protected] ; Garcia-España Monsonis, Enrique, [email protected] ; Soriano Soto, Concepción, [email protected]
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